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Potentiodynamic and galvanostatic experiments have been used to investigate the electrodeposition of Zn and to develop a reliable recovery method from a purified spent pickling liquor (SPL) of hot dip galvanization. The main bjective was to find the suitable conditions to deposit high-grade Zn from the purified ZnCl2–HCl–NaCl solution in a conventional electrowinning cell holding the stationary electrolyte. The effects of pH (1.5–4.5) in and Zn concentration (30–150 g/dm3) in the stationary electrolytes were studied first by the potentiodynamic method to reveal the major characteristics of the cathodic process and to give reference for further practical examinations by the galvanostatic technique. The electrowinning experiments pointed out the effects of these major parameters, beside other practical factors, like apparent current density (c.d.) and additional NaCl concentration. The long-term galvanostatic experiments proved that the current efficiency (c.e.) increases significantly as the pH and the Zn concentration are increased. A c.e. of ~ 99% can be reached with an electrolyte of pH ~ 5, Zn concentration ~ 50 g/dm3 applying a c.d. in the 300–600 A/m2 range. Increasing the Zn concentration could considerably improve also the deposit morphology. The addition of NaCl can practically improve the c.e. if the Zn concentration is at least around 50 g/dm3. In contrast, this improvement is largely off-set by the negative effects of strong H2 evolution at low (e.g. < 10 g/dm3) Zn concentrations. Extremely high Cl− ion concentrations, however, inhibit the cathodic reaction by stronger chloro-complex formation. In this case the intensive H+ reduction causes hydroxide precipitation.Article Highlights: The evolution of hydrogen and the reduction of Zn2+ are reflected in polarization curves and the development of surface irregularities at the cathode. The current efficiencies and the surface morphologies were determined with different electrolyte compositions in a wide range of apparent current densities. A pH values in the range of 2–5 and apparent current densities of 600–1200 A/m2 were found suitable to avoid excessive hydrogen evolution and hydroxide precipitation. Sodium chloride addition enhances chloro-complexation of zinc, promotes hydroxide precipitation and hydrogen evolution. [ABSTRACT FROM AUTHOR]

The ICT-OEC Cu–Cl cycle is a six-step thermochemical copper-chlorine (Cu–Cl) closed-loop cycle to produce green hydrogen via water splitting. One of the critical steps in this cycle involves the electrolysis of CuCl to generate copper (Cu) and cupric chloride (CuCl 2). Using platinum as the anode material in this system is economically disadvantageous and expensive. Consequently, this work investigates the feasibility of alternative anode materials to replace platinum. Mixed Metal Oxide (MMO) coated on Ti mesh (MMO mesh) and Pt coated on Ti mesh (Pt mesh) were evaluated as suitable anode alternatives to pure Pt sheet based on their performance metrics at different voltages. The integration of MMO mesh for a 100-h Time on Stream (TOS) study at a mini-pilot scale demonstrated promising current density and efficiency values. However, performance variations were observed over prolonged operation, potentially due to changes in membrane resistance. After 100 h, the MMO mesh remained undamaged, indicating its durability for extended use. Characterization studies revealed the electrodeposited copper to have a dendritic structure with an FCC phase. The findings suggest that MMO mesh and Pt mesh are viable alternatives to platinum at operating voltages above 0.7 V in this system. [Display omitted] • Anode material investigations for green H 2 production in CuCl electrolysis. • Mixed Metal Oxide (MMO) or Pt coated on Ti-mesh are viable alternatives to pure Pt. • Alternative anodes at voltage above 0.7 V yield high efficiencies. • MMO mesh in mini-pilot single cell assembly operated for 100 h, indicates durability. • Potential to lower CuCl electrolysis voltage, boosting ICT-OEC Cu–Cl cycle efficiency. [ABSTRACT FROM AUTHOR]

This work presents an external capacitor‐less low‐dropout regulator (CL‐LDO) with high power supply rejection (PSR) over a wide frequency and load current (IL) range. The high PSR is implemented with an adaptive supply‐ripple cancellation (ASRC) technique. The proposed ASRC circuit consists of a buffer with diode‐connected structure and an adjusting unit. The novel buffer introduces the supply ripple through the diode‐connected transistor to the gate of the pass transistor, enhancing the PSR in the range of 1 MHz. Additionally, the adjusting unit trims the current of the buffer continuously according to the magnitude of IL to optimize the PSR adaptively. Designed in a 55 nm CMOS process with an input voltage of 1.4 V, the proposed LDO achieves −69 dB and −55 dB PSR at 100 KHz and 1 MHz for 50 mA of IL, respectively. Moreover, the maximum current efficiency of the LDO is 99.8% at a full IL of 50 mA. [ABSTRACT FROM AUTHOR]

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This study aims to explain the effect of adding the bioactive substance (alpha enzyme) to the electrolyte solution using electrochemical deposition. Through which copper nanoparticles are manufactured, the originality of the research lies in the presence of this addition as a new method in manufacturing nanoparticles in an electrochemical manner, as the alpha-amylase enzyme is extracted from camel saliva, and the product has been diagnosed using (EDX) and scanning electron microscope (FE-SEM) techniques. , Dynamic Light Scattering (DLS) technology, and Zeta potential. The proposed method is an easy, inexpensive, and environmentally friendly method where the alpha enzyme was used as a feedstock at concentrations of (0.25, 0.50, 0.57, and 1) g added to a solution containing the ideal sample obtained through the electrochemical precipitation process before adding the enzyme, as the solution before The addition process contains concentrated sulfuric acid (H2SO4) at concentrations of (20, 30, 40, 50 and 60) g/ml. The regular shape and stable distribution can be observed after the addition compared to the shape of the particles before the addition in terms of shape and size. The process was carried out under constant conditions, including the current. Direct, voltage and temperature, and after the addition process, sulfuric acid was dispensed with, while the process conditions with the addition were at a temperature of 37 degrees Celsius and an incubation period that lasted a full hour before the electrodeposition process was carried out in accordance with the enzyme activity conditions, where a nanosized copper powder of a granular size was obtained. Approximately 44 nanometers. It is worth noting that the nanoparticle size was modulated using the experimental conditions, e.g., pH, reducing step, enzyme amount, or incubation time. This controlled synthesis allows the preparation of CuNP bionanoparticles at Cu 3.13 powder at a concentration of 80 g CuSO4 + 0.50 α-amylase.

Electrolytic manganese is an important metal material that is widely employed in batteries, electronics, steel, and other fields. However, there are many issues regarding the production process of electrolytic manganese, such as low current efficiency, high-content toxic SeO2 additives in the electrolyte, and difficulty in controlling the product morphology. These issues not only impact the production efficiency and quality of electrolytic manganese but also result in severe environmental pollution. To address these issues, a MnSO4-(NH4)2SO4 electrolyte system was prepared based on the electrolytic manganese industry standard. The effects of polyacrylic acid, glycine, ethylenediaminetetraacetic acid (EDTA), and gluconic acid were explored as auxiliary additives under neutral electrolysis conditions to lower the SeO2 content, which is a highly toxic main additive. The effects of the different additives on the metal manganese morphology, crystal structure, and cathodic electrochemical polarization behavior were examined by field-emission scanning electron microscopy, X-ray diffraction, and constant current cathodic polarization curve tests. The findings reveal that the main orientation of the metal manganese crystal form deposited by the four auxiliary additives is the (330) crystal plane, and all of them can promote the formation of α-Mn, enhance the electrolysis efficiency, and lower the energy consumption. In particular, the optimized amount of polyacrylic acid of 0.08 g·L−1 contributes to an energy consumption of 5735.34 kW·h·t−1. Correspondingly, the addition of 10 g·L−1 glycine is the most favorable amount, leading to an energy consumption of 5518.56 kW·h·t−1. For EDTA, the lowest energy consumption of 5168.26 kW·h·t−1 is measured at an added amount of 0.5 g·L−1. Note that among the four investigated candidates, gluconic acid is the most favorable auxiliary additive, contributing to the increased cathode current density and reduced cathodic polarization as well as denser metal manganese products. Moreover, gluconic acid addition can lower the concentration of toxic SeO2 from 0.03–0.06 to 0.015 g·L−1, significantly increase the cathode current density, reduce the cathodic polarization, and result in a more dense and smooth product morphology, with the current efficiency being increased from approximately 70% to 89.73% and energy consumption being reduced from 6500 to 4990.58 kW·h·t−1 at the same time. Gluconic acid, as the auxiliary additive, not only contributes to the best electrolysis indexes for electrolytic manganese but also facilitates the formation of metal manganese with the most desirable crystal structure. This work offers novel insights into the environmentally friendly production and cheap electrodeposition of metal manganese for the electrolytic manganese industry.

The cooling curves of the Al–Zn–In–Mg–Ag alloys in copper mold, iron mold, and 400 °C-preheated iron mold cast were simulated and three solidification rates were calculated to be 7.05 °C/s, 0.76 °C/s, and 0.28 °C/s. The effects of cooling rate on the microstructure, electrochemical characteristics, and corrosion morphologies of Al–Zn–In–Mg–Ag alloys are investigated. The results demonstrate that the alloy with a low cooling rate has the lowest self-corrosion rate (0.09 mm/year), the highest actual capacity (2503.16 Ah/Kg2), as well as the highest anode current efficiency (87.46%). The anode current efficiency of the Al alloys is affected by the self-corrosion and the detachment of the second phases and grains. As the cooling rate decreases, the grain size becomes larger, the amount of the MgZn2 second phase decreases, and the content of In, Zn, and Ag activation elements increases in the matrix. The corrosion of the Al–Zn–In–Mg–Ag alloy initiates from the micro-galvanic corrosion between the MgZn2 second phase and the Al matrix. It then extends along the grain boundaries and towards the intragranular, accompanied by the shedding of the MgZn2 particles and the grains.

This study explores the electrochemical reduction of carbon dioxide (CO2) using tin (Sn) and zinc (Zn) catalyst-loaded gas diffusion electrodes (GDEs). The research explores the influence of electrolytic potential and catalyst loading on the efficiency of CO2 conversion to valuable chemicals, specifically formic acid and carbon monoxide. The best Sn loading for Sn-loaded GDEs, according to the morphological study, is 7 mg.cm-2, which results in higher current density (0.33 mA.cm-2) and current efficiency (36%). An electrolytic potential of -1.3 V Vs. Ag/AgCl is identified as optimal for Sn GDEs, offering a balance between high current efficiency (35%) and controlled current density. For Zn-loaded GDEs, an optimal loading of 5 mg.cm2- yields the highest current efficiency of 19.4% and a peak current density of 0.28 mA.cm2- at an electrolytic potential of -1.55 V Vs. Ag/AgCl, in addition to highlighting the crucial role that catalyst loading and electrolytic potential play in enhancing CO2 reduction efficiency, this research offers insightful information for environmentally friendly CO2 conversion technology. [ABSTRACT FROM AUTHOR]

This study investigates the effect of temperature on the rate of the oxygen evolution reaction (OER) during the electrochemical production of ferrate(VI) through anodic iron dissolution. We employed a membrane-divided electrochemical cell with a galvanostatically operated three-electrode setup. During the experiments, we recorded the anode potential at various temperatures and monitored temperature variations over time. Simultaneously, we measured the rates of ferrate(VI) formation and the oxygen evolution reaction. The latter, considered a parasitic reaction, competes with ferrate synthesis. By quantifying the extent to which the OER consumed the applied charge, we discovered that the OER rate decreases with temperature. Specifically, at 25 °C and 168 Am−2, the OER consumes more than double the charge of the produced ferrate, at higher temperatures the rate sensibly decays and with it the consumed charge by the OER. The specific energy required for ferrate(VI) production decreases as temperatures increase, aligning well with current efficiency and space-time yield values within the same temperature range.

Water pollution is becoming more and more serious nowadays, and water resources are in shortage. As an environmentally friendly wastewater treatment technology without secondary pollution, the three-dimensional electrode method has received more and more attention. However, the conventional direct current (DC) three-dimensional electrode method has the disadvantages of high energy consumption and low current efficiency. Based on this, this work investigated the treatment of malachite green (MG) dye wastewater by pulse three-dimensional electrode method. The influences of pulse duty cycle, pulse period, electrolysis voltage, initial pH, aeration rate and Na2SO4 concentration on MG degradation were investigated. The results showed that under the optimal operating conditions of pulse duty cycle of 0.4, pulse period of 15 s, electrolysis voltage of 15 V, initial pH of 5, aeration rate of 0.5 L/min, Na2SO4 concentration of 0.10 mol/L, the removal rates of MG and COD reached 96.2% and 80.5%, respectively, the current efficiency reached 93.4%, and the energy consumption was 24.2 kWh/kg COD after 150 min. Compared with DC power supply mode, the MG removal rate, COD removal rate and current efficiency were enhanced, and the energy consumption was reduced by 83.9%. Moreover, the generation capacity of ·OH was increased under pulse power supply mode. Finally, a possible degradation pathway of MG in pulse power supply mode was inferred using UV-vis and GC-MS analysis. This study indicates that the pulse three-dimensional electrode method is an efficient and low-energy-consumption wastewater treatment method with stable degradation performance for MG dye wastewater. [ABSTRACT FROM AUTHOR]

The Ti-5Al-2Sn-4Zr-4Mo-2Cr-1Fe (β-CEZ) alloy is considered as a potential structural material in the aviation industry due to its outstanding strength and corrosion resistance. Electrochemical machining (ECM) is an efficient and low-cost technology for manufacturing the β-CEZ alloy. In ECM, the machining parameter selection and tool design are based on the electrochemical dissolution behavior of the materials. In this study, the electrochemical dissolution behaviors of the β-CEZ and Ti-6Al-4V (TC4) alloys in NaNO3 solution are discussed. The open circuit potential (OCP), Tafel polarization, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and current efficiency curves of the β-CEZ and TC4 alloys are analyzed. The results show that, compared to the TC4 alloy, the passivation film structure is denser and the charge transfer resistance in the dissolution process is greater for the β-CEZ alloy. Moreover, the dissolved surface morphology of the two titanium-based alloys under different current densities are analyzed. Under low current densities, the β-CEZ alloy surface comprises dissolution pits and dissolved products, while the TC4 alloy surface comprises a porous honeycomb structure. Under high current densities, the surface waviness of both the alloys improves and the TC4 alloy surface is flatter and smoother than the β-CEZ alloy surface. Finally, the electrochemical dissolution models of β-CEZ and TC4 alloys are proposed. [ABSTRACT FROM AUTHOR]

Iron-rich electrolytic manganese residue (IREMR) is an industrial waste produced during the processing of electrolytic metal manganese, and it contains certain amounts of Fe and Mn resources and other heavy metals. In this study, the slurry electrolysis technique was used to recover high-purity Fe powder from IREMR. The effects of IREMR and H2SO4 mass ratio, current density, reaction temperature, and electrolytic time on the leaching and current efficiencies of Fe were studied. According to the results, high-purity Fe powder can be recovered from the cathode plate, and the slurry electrolyte can be recycled. The leaching efficiency, current efficiency, and purity of Fe reached 92.58%, 80.65%, and 98.72wt%, respectively, at a 1:2.5 mass ratio of H2SO4 and IREMR, reaction temperature of 60°C, electric current density of 30 mA/cm2, and reaction time of 8 h. In addition, vibrating sample magnetometer (VSM) analysis showed that the coercivity of electrolytic iron powder was 54.5 A/m, which reached the advanced magnetic grade of electrical pure-iron powder (DT4A coercivity standard). The slurry electrolytic method provides fundamental support for the industrial application of Fe resource recovery in IRMER. [ABSTRACT FROM AUTHOR]

The aim of copper hydrometallurgy is to produce high-quality cathode copper with the lowest energy consumption and the highest current efficiency. How to achieve this objective has become the focus of research. The anode material significantly influences the anode overpotential, current efficiency and cathode copper quality. Therefore, developing energy-saving anodes holds great practical significance for the copper electrowinning industry. The introduction of alloying element such as Ag, Ca, Co and Re into the lead alloy anode can enhance the mechanical strength of lead alloy, inhibit lead dissolution, and improve its electrocatalytic activity and corrosion resistance; the fabrication of composite anodes with active layers such as β-PbO2, IrO2-Ta2O5, TiB2/β-PbO2 and Co3O4 on conductive substrates, which possess excellent conductivity and catalytic activity, can enhance the anode’s corrosion resistance and reduce the oxygen evolution overpotential; it is found that graphite, lead with a three-dimensional structure and the PANI/Co3O4 composite can enhance both the active specific surface area and current efficiency of anode. By adjusting the copper acid ratio in the electrolyte from 0.25 to 0.30, and adding guar gum, thiourea and Co2+, the performance of the anode can be enhanced and the quality of the cathode copper can be improved. Furthermore, optimizing process conditions such as the temperature of the electrolyte and electrode spacing can also impact the anode’s lifespan and catalytic activity. In this paper, energy-saving measures for hydrometallurgical copper refining were mainly introduced from three aspects: the development of oxygen-evolving anodes, adjustments to the solution system, and optimization of process parameters. Finally, the future development direction of energy-saving in copper electrowinning was discussed.

NaBH 4 is a promising hydrogen storage material, while faced with enormous difficulties for scale-up application due to regeneration issues. In this study, a highly efficient and economical strategy for the electrosynthesis of NaBH 4 from hydrolysis by-product NaB(OH) 4 has been proposed. By fabricating solid-phase electrodes with NaB(OH) 4 and electrocatalyst etc., the mass transfer process of B(OH) 4 - at the cathode surface was remarkably improved, thus reducing the resistance of the cathodic reaction. Meanwhile, XPS, FTIR, and CV analyses were combined to reveal the reaction path and control steps of B(OH) 4 - reduction to BH 4 − in the electrocatalytic system. The formation of NaBH 4 and intermediates (BH(OH) 3 -, BH 2 (OH) 2 -, and BH 3 (OH)-) is the gradual replacement of (OH)- in NaB(OH) 4 by H−. Furthermore, this study reveals that PbO has a suitable hydrogen evolution overpotential and excellent selective catalytic activity. The current efficiency for NaBH 4 synthesis via solid-phase electrolysis was up to 68.12 % by systematically regulating various factors. [Display omitted] • An efficient method for synthesizing NaBH 4 was developed by solid-phase electrolysis. • Reaction routes and control steps of B(OH) 4 - electroreduction were revealed. • Core-shell structural cathode design promoted the conversion of intermediates. • PbO presented excellent selective electrocatalytic activity for B(OH) 4 - reduction. • The formation of NaBH 4 is the gradual replacement of (OH)- in NaB(OH) 4 by H−. [ABSTRACT FROM AUTHOR]

The improved luminescence and colour purity of solution‐processable perovskite materials have positioned them as promising candidates for advanced lighting technologies. Herein, a simple method is presented for fabricating dual hole‐transport layers (HTLs) of green perovskite light‐emitting diodes (PeLEDs), for improved charge balance in the emissive layer (EML). With well‐matched energy levels, and lowered charge injection barrier of the transport layers, maximum radiative recombination in the EML can be obtained. The varying highest occupied molecular orbital (HOMO) levels of the HTLs used in the device are in alignment with the work function of the fluorine‐doped tin oxide and HOMO of the EML. The poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate)/N,N′‐bis(naphthalen‐1‐yl)‐N,N′‐bis(phenyl)‐2,2′‐dimethylbenzidine (PEDOT:PSS/NPD)‐based PeLED device shows outstanding performance with a maximum brightness of 19625 cd m−2, highest current efficiency of 19.2 cd A−1, and turn‐on voltage of 3.8 V among the all HTL combinations. These improvements are attributed to the well‐matched HOMO of NPD and PEDOT:PSS, with both the anode and EML allowing improved hole injection and charge balance. Electroluminescence supports the coordinates (0.22, 0.74) for pure green emission provided by the Commission Internationale de I'Eclairage. Perovskite films fabricated on top of PEDOT:PSS/NPD have the best film morphology and crystallinity with the fewest pinholes enabling improved charge transport. [ABSTRACT FROM AUTHOR]

Recent research is investigating deoxidation electrolysis for eco‐friendly iron extraction. However, many parameters are not fully understood and inconsistencies in reported Faradaic efficiencies pose challenges for finding the most suitable experimental conditions. Thus, we investigated the dependence of hematite reduction efficiency on process parameters and cell configurations. Firstly, we studied the influence of the anode material. The experiments included cyclic voltammetry to identify the redox potentials, electrolysis, and X‐ray diffraction followed by Rietveld refinement to analyze the pellets after electrolysis. In some cases, scanning electron microscopy equipped with energy‐dispersive X‐ray spectroscopy was employed to track the elemental map of the cathode pellets. Nickel/iron alloy, a well‐known oxygen‐evolving electrocatalyst material, clearly outperformed other anode materials, namely graphite, titanium, nickel, and platinum. Subsequent investigations explored the impact of an inert atmosphere and anode‐cathode decoupling on Faradaic efficiency. The findings indicated that the decline in Faradaic efficiency cannot be solely attributed to the hydrogen evolution reaction, but also to other parasitic effects such as carbon cycles. Additionally, we employed energy consumption measurements as a mean of comparing the process against established extractive methodologies. The required energy consumption by electrolysis is up to 46 % lower than that of a blast furnace. [ABSTRACT FROM AUTHOR]

Fe–Ni invar alloy (Fe 64–Ni 36 wt%) has a very low coefficient of thermal expansion (CTE) than any other metals. For this reason, it has been used as fine metal mask (FMM) in RGB patterning of OLED manufacture process. However, as the resolution of OLED display is getting higher, the thickness of FMM is getting thinner and then the conventional extruded invar sheet cannot be used directly. The electrodeposition of invar can be the alternative for fabrication of thin FMM. In this study, the Fe–Ni alloy were electrodeposited varying bath compositions and current density. Also, the effects of ferric ion (Fe3+), produced during electrodeposition on inert anode, on the behavior of deposition were investigated. Finally, the Fe–Ni alloy with 36–40 wt% Ni were obtained at 50 mA/cm2 in 0.30 M Fe2+ bath. The back side and front side composition of the deposits were analyzed to evaluate the composition uniformity of the Fe–Ni alloys. Generally, the Fe content of back side of the deposits were higher than that of front side. [ABSTRACT FROM AUTHOR]

The treatment of oily wastewater is a critical environmental concern, and electrocoagulation (EC) has emerged as an effective method for reducing chemical oxygen demand (COD) from this type of wastewater. This study investigates the effectiveness of continuous electrocoagulation in removing COD from real oily wastewater using a cathode configuration electrode between two tubular anodes coupled in a monopolar-parallel fashion to a DC power source. The research compares the removal efficiency, current efficiency, and operating cost of One-Sided Finned cathode (1SF) made from aluminum and Two-Sided Finned cathode 2SF made from stainless steel. The operating parameters considered are electrolysis time, current density, and flow rate. The results indicate that the elimination effectiveness of chemical oxygen demand (COD) employing 2SF was higher than that achieved with 1SF, with removal efficiencies of 93% and 82%, respectively. The operating cost of the 2SF was slightly higher than the (1SF), at 0.738 ($/m3) and 0.660 ($/m3), respectively. The current efficiency and Ohmic drop (ohm) were also higher for the 2SF than the 1SF. The order of the 1SF and 2SF was first-order, and both configurations were exothermic. The study provides valuable insights for enhancing COD removal via EC process including Two-Sided Finned cathode due to the larger active area provided by the 2SF design then the enhancement of providing huge amount of hydroxide ions required to increase electro-coagulants quantity compared to that provided by using One-Sided Finned cathode.

Abstract Recent research is investigating deoxidation electrolysis for eco‐friendly iron extraction. However, many parameters are not fully understood and inconsistencies in reported Faradaic efficiencies pose challenges for finding the most suitable experimental conditions. Thus, we investigated the dependence of hematite reduction efficiency on process parameters and cell configurations. Firstly, we studied the influence of the anode material. The experiments included cyclic voltammetry to identify the redox potentials, electrolysis, and X‐ray diffraction followed by Rietveld refinement to analyze the pellets after electrolysis. In some cases, scanning electron microscopy equipped with energy‐dispersive X‐ray spectroscopy was employed to track the elemental map of the cathode pellets. Nickel/iron alloy, a well‐known oxygen‐evolving electrocatalyst material, clearly outperformed other anode materials, namely graphite, titanium, nickel, and platinum. Subsequent investigations explored the impact of an inert atmosphere and anode‐cathode decoupling on Faradaic efficiency. The findings indicated that the decline in Faradaic efficiency cannot be solely attributed to the hydrogen evolution reaction, but also to other parasitic effects such as carbon cycles. Additionally, we employed energy consumption measurements as a mean of comparing the process against established extractive methodologies. The required energy consumption by electrolysis is up to 46 % lower than that of a blast furnace.

One of the most effective methods to produce ferrate ions (FeO42–) is electrochemical synthesis. During the transpassive anodic dissolution of iron, the formation of ferrate ions and the evolution of oxygen occur simultaneously, and only the sum of the currents generated by the two processes can be observed in the voltammetric curves. Products of the above process have been investigated in 45 % (m/m) aqueous NaOH solutions by using the dual dynamic voltammetry (DDV)&rotating ring-disk electrode (RRDE) method (i.e., applying dynamic potential programs to the disk and the ring electrodes of the RRDE disk electrode and the RRDE ring electrode simultaneously) combined with spectrophotometric measurements. Fe disk/Pt ring and Pt disk/Pt ring RRDE tips were used in the voltammetric experiments. The electrode potential regions where ferrate ions and oxygen are forming could effectively be identified. The results imply that, under the applied experimental conditions, the oxygen evolved at the disk cannot be reduced at the ring. This can be explained by the fact that elemental oxygen practically does not dissolve in concentrated aqueous sodium hydroxide solutions due to the “salting-out effect”. By using the dual voltammetric method, it was also possible to determine the optimal potential range for the electrochemical production of ferrate ions in terms of charging efficiency. The latter quantity has an important impact on the economics of practical applications. The approach proposed in this study proved to be very promising for the simultaneous detection of different dissolution products.

To date, reactor-grade zircon is produced on an industrial scale using metallothermic and electrochemical methods. Electrolytic production of reactor-purity zirconium in a sealed electrolyzer is more cost-effective than metallothermic production, as it does not require iodide refining and the use of reducing metals (Na, Mg, and Ca). Despite the importance of this production, its features are not fully described in the literature. This study presents the results of industrial tests of the electrolysis process in a sealed electrolyzer with a current load of 10 kA from the molten electrolyte KC1--KF--K2ZrF6. Based on the achieved technological indicators, the current efficiencies of the main cathode and anode reactions were determined and the factors influencing them were evaluated. We analyzed the composition of nutrient salts and the mechanism of accumulation of potassium fluoride in the electrolyte, an increase in which concentration leads to an anode-destroying effect. We considered possible mechanisms of the electrochemical formation of freons and compiled material balances for all starting substances and reaction products. The change in the electrolyte density during electrolysis was calculated, which allowed justifying the volume of its daily drainage. Fine carbon and zirconium powder formed in the electrolyte due to the interaction with potassium metal are not separated and are removed for chemical redistribution, which reduces the productivity of the electrolysis process. [ABSTRACT FROM AUTHOR]

The focus of an amplifier's design engineer is always on its high gain and bandwidth. While larger transistors can produce higher gains, the trade-off is a narrower bandwidth. On the other hand, increasing an amplifier's DC biassing current results in an increase in its bandwidth, but at the expense of higher power consumption. In order to resolve these conflicts, a new structure for dual output operational transconductance amplifier (DOOTA) using current splitting technique has been proposed in this paper. Current splitting concept has been introduced to obtain two different paths for signal current. The proposed current-splitter DOOTA (CS-DOOTA) requires considerably lower count of circuit components. It shows significant increase in bandwidth, while requiring lower operating current, leading to considerable improvements in small-signal figure of merit. Furthermore, to obtain higher transconductance and slew rate, an improved current splitter-DOOTA (ICS-DOOTA) is proposed. The parameters of this ICS-DOOTA can be improved by increasing the splitting ratio (K) of the MOSFETs. This architecture shows improvements in large-signal figure of merit, due to improvement in its slew rate with higher values of K, while possessing the same dimensions and biasing current. All these results have been verified using Ltspice, in 0.18 µm technology. A high gain CDTA has been implemented using ICS-DOOTA, which is further used in the realization of current-mode KHN filters with different current splitting factors. [ABSTRACT FROM AUTHOR]

A desire to achieve optimal electron transport from the electron transport layer (ETL) towards the emissive layer (EML) is an important research factor for the realization of high performance quantum dot light-emitting diodes (QD-LEDs). In this paper, we study the effect of a single, double, and electron transport layer sandwiched Poly(4-vinylpyridine) (PVPy here on) on the charge injection balance and on the overall device performance of InP-based red quantum dot light emitting diodes (red QD-LEDs). The results showed general improvement of device characteristic performance metrics such as operational life with incorporation of a PVPy interlayer. The best performance was observed at a lower concentration of PVPy (@ 0.1 mg/mL) in interlayer with continual worsening in performance as PVPy concentration in the interlayer increased in other fabricated devices. The AFM images obtained for the different materials reported improved surface morphology and overall improved surface properties, but decreased overall device performance as PVPy concentration in interlayer was increased. Furthermore, we fabricated two special devices: in the first special device, a single 0.1 mg/mL PVPy sandwiched between two ZnO ETL layers, and in the second special device, two 0.1 mg/mL PVPy interlayers were inter-sandwiched between two ZnO ETL layers. Particular emphasis was placed on monitoring the maximum obtained EQE and the maximum obtained luminance of all the devices. The first special device showed better all-round improved performance than the second special device compared to the reference device (without PVPy) and the device with a single 0.1 mg/mL PVPy interlayer stacked between ZnO ETL and the emissive layer. [ABSTRACT FROM AUTHOR]

A cyanide-free copper(I)-based bath for direct electroplating on steel substrate was developed. The effect of thiourea as complexing agent on the electrodeposition of copper(I) ion was studied electrochemically. The adhesion, surface morphology, elemental composition, and phase structure of the electroplated copper coating were characterized by cross-cut testing, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD), respectively. The results showed that thiourea could form a stable complex with Cu(I) ion, resulting in a much more negative deposition potential of Cu(I) ion, and avoiding the displacement reaction between copper and iron when conducting the electrodeposition of copper directly on steel substrate. The given bath had a wide range of working current density at a temperature not lower than 60 °C. Both cathodic and anodic current efficiencies of the bath are higher than 95%. A smooth, compact, fine-grained, highly pure, and well-adhered copper coating could be electrodeposited directly on steel in the given bath. [ABSTRACT FROM AUTHOR]

Liquid desiccant air-conditioning system is an energy-efficient choice for heat and moisture independent treatment in buildings, especially for the large dehumidification load. Electrodialysis regeneration is a novel and reliable regeneration method for liquid desiccants, which is suitable for hot and humid climates. In this paper, the performance of the electrodialysis regenerator for regenerating lithium chloride and lithium bromide solutions was studied experimentally, and the current efficiency of the electrodialysis regenerator for regenerating these two solutions was compared. Through analysis, the solute molecular weight was coupled into the current efficiency model, and a new current efficiency model of electrodialysis regenerator for regenerating these two solutions was established, which considers the solute molecular weight of liquid desiccant and can be extended to more liquid desiccants in the future. Furthermore, the performance of the liquid desiccant air-conditioning system using electrodialysis regeneration with these two solutions is compared based on this model. The results show that when lithium chloride solution is applied as liquid desiccant, the system performance coefficient (COP, ratio of cooling capacity to energy consumption) is between 1.16 and 4.49, while the performance coefficient of the system is between 2 and 8.3 when the system uses lithium bromide solution. [ABSTRACT FROM AUTHOR]

Wastewater treatment and removal of heavy metals are of great importance, especially in terms of industry, economy, environment and public health. Electrodialysis desalination mode is an effective process for treating metals in contaminated solutions and for further recovery of metals to new uses. In this work, the removal of copper ions from solution using a recirculating electrodialysis system was studied. Different factors affecting ED performance, such as applied voltage, pH, flow rate, and metal ion concentration on metal removal efficiency, energy consumption, and current efficiency were investigated. The stainless-steel 316 (SS 316) electrode was used as an anode and a cathode and has the advantage of a low corrosion rate. The optimum conditions for 99.59 % removal of 200 mg/L of copper in 60 min are 18 V, pH 4, and a flow rate of 800 ml/min to produce a dilute solution of 0.83 mg/L Cu2+ (<1.3 mg/L), which is within the acceptable limits and suitable for discharges into the environment. Additionally, the current efficiency was 87.78%, the flux was calculated to be 7.84 µmol/m2m, and the energy consumption was 1.73 Wh/L. The study shows that the electrodialysis method can be used efficiently for the removal of copper ions from wastewater. [ABSTRACT FROM AUTHOR]

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Quantum dot light‐emitting diodes (QLEDs) are considered promising candidates for several optoelectronic applications; however, they are plagued by the over‐injection of electrons compared to holes, which limits device efficiency. Studies have attempted to reuse the leaked electrons and transfer recombination energies via inserting an exciton‐harvesting layer (EHL) between the emissive layer (EML) and hole transport layer (HTL). This study conducts a detailed analysis of the energy transfer mechanisms to obtain better insights into improving the device performance. First, by analyzing the electroluminescence (EL) spectra and exciton dynamics, the effect of EHLs comprising phosphorescence (PH) or thermally activated delayed fluorescence (TADF) blue dopant is compared. Through parallel incorporation of those EHLs on QLEDs and organic LEDs, the minimal contribution of the PH‐EHL to energy transfer in QLEDs is confirmed, whereas the TADF‐EHL has a significant contribution. Second, highly efficient top‐emission green QLEDs with the TADF‐EHL are achieved. They exhibit a maximum luminance (L) and current efficiency (CE) of 40700 cd m−2 and 68.0 cd A−1, respectively, which are the highest among the reported values for green‐emitting InP QLEDs. The proposed approaches are expected to provide aid in the realization of highly efficient QLEDs from the analysis to the device optimization stage. [ABSTRACT FROM AUTHOR]

The gallium electrowinning process is always accompanied by hydrogen evolution reaction that results in low current efficiency (CE). In this manuscript, cyclic voltammetry and chronoamperometry studies were carried out to investigate the gallium cathode behavior under various conditions and explore the parameter that is beneficial to improve the CE. The CE of the lead and copper cathodes was higher, while gallium deposited on the titanium, SUS316, and SUS304 cathodes was readily separated. Increasing the overpotential and gallium concentration or decreasing the pH within a certain range was all beneficial to improve the CE, while the temperature had no significant effect on the CE. Kinetic studies of gallium electrodeposition were carried out. The gallium electrodeposition process was determined as mixed control and forced convection is expected to further improve the CE. The apparent activation energy and kinetic current from the electrochemical reactions were determined to be 23.335 kJ mol−1 and 47.6 mA, respectively. [ABSTRACT FROM AUTHOR]

In mass production OLED structures, doping ratio distribution across the thickness of emitting layer is not uniform owing to the linear evaporating configuration, where dopant and host materials are added in different sources. In this study, we firstly confirmed that different types of doping distribution among emitting layer of green phosphorescent OLED exhibited over 15% difference of current efficiency. By carefully designing and comparing emitting layers with a series of doping distribution modes, we found that dramatic variation of doping ratio near electron blocking layer was the critical factor. Then, trapping behavior of dopant molecules was confirmed to affect the carrier distribution among the emitting layer according to analysis of current density‐voltage (JV) and capacitance‐voltage (CV) curves from carrier only devices based on two types of doping distribution modes. Combining with the result of hole‐electron recombination zone (RZ), the area where possessed both high doping ratio and excitons recombination probability exhibited a high current efficiency and low driving voltage. Finally, PL and EL transient decay lifetime combined with triplet‐polaron quenching (TPQ) efficiency measurement demonstrated that TPQ was the main factor causing current efficiency difference between two types of doping distribution modes. Therefore, the doping distribution and trapping property of dopant material in emission layer should be carefully evaluated for OLED devices for mass production. [ABSTRACT FROM AUTHOR]

To keep up with the development of contaminants in the water supply, it is required to create new adsorbents or improve current ones. The adsorption capacity of AlPO4 electrocoagulated with varying current intensities was examined. AlPO4 was produced by electrolysis in a NaCl solution using aluminum electrodes and a 0.1 M phosphate buffer at varying current intensities. Current efficiency was enhanced. X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy were used to analyze the adsorbents (FTIR). The specific surface area was estimated by the quantity of methylene blue adsorbed by particles in an aqueous solution. Numerous operating factors must be addressed, including pH, starting concentration, adsorbent dose, and contact duration. The electrostatic interaction between positively charged MB molecules and negatively charged adsorbents drives adsorption at alkaline pH. When describing equilibrium adsorption, the Langmuir model is more accurate. Modeling using an adsorption isotherm may further improve the predicted specific surface area. At 0.2 amperes, the observed specific surface area was 2.86 m2/g. [ABSTRACT FROM AUTHOR]